bisecting fixing commit since d45331b00ddb179e291766617259261c112db872 building syzkaller on 8620c2c2581732b54045bd75ae1220982fbb650f testing commit d45331b00ddb179e291766617259261c112db872 with gcc (GCC) 8.1.0 kernel signature: 4b07b95342639e10b88010283ca52a805a95732c24e3e567fca0568eeb8a5b2f run #0: crashed: INFO: task hung in acct_collect run #1: crashed: INFO: task hung in acct_collect run #2: crashed: INFO: task hung in acct_collect run #3: crashed: INFO: task hung in acct_collect run #4: crashed: INFO: task hung in do_exit run #5: crashed: INFO: task hung in do_exit run #6: crashed: INFO: task hung in do_exit run #7: crashed: INFO: task hung in do_exit run #8: crashed: INFO: task hung in do_exit run #9: crashed: INFO: task hung in do_exit testing current HEAD c578ddb39e565139897124e74e5a43e56538cb33 testing commit c578ddb39e565139897124e74e5a43e56538cb33 with gcc (GCC) 8.1.0 kernel signature: d6fa4afe4c23fec70ab5ffb95e5b9d5df023abca0bc34f687108d5186bb401c9 all runs: crashed: INFO: task hung in do_exit revisions tested: 2, total time: 26m8.08834869s (build: 12m54.419693111s, test: 12m27.022890832s) the crash still happens on HEAD commit msg: Merge tag 'linux-kselftest-5.7-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest crash: INFO: task hung in do_exit INFO: task syz-executor.3:7737 blocked for more than 143 seconds. Not tainted 5.7.0-rc2-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D27320 7737 6856 0x80004004 Call Trace: context_switch kernel/sched/core.c:3372 [inline] __schedule+0x85b/0x1950 kernel/sched/core.c:4088 schedule+0xc3/0x2b0 kernel/sched/core.c:4163 rwsem_down_read_slowpath+0x568/0xfd0 kernel/locking/rwsem.c:1099 __down_read kernel/locking/rwsem.c:1341 [inline] down_read+0x1f5/0x430 kernel/locking/rwsem.c:1494 exit_mm kernel/exit.c:445 [inline] do_exit+0x5e9/0x2bf0 kernel/exit.c:782 do_group_exit+0xf4/0x2e0 kernel/exit.c:893 get_signal+0x36c/0x1d30 kernel/signal.c:2735 do_signal+0x87/0x28d0 arch/x86/kernel/signal.c:784 exit_to_usermode_loop+0x114/0x2e0 arch/x86/entry/common.c:161 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_64+0x531/0x630 arch/x86/entry/common.c:305 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x45987a Code: 89 f5 41 54 49 89 fc 55 53 74 35 49 63 e8 48 63 da 4d 89 f9 49 89 e8 4d 63 d6 48 89 da 4c 89 ee 4c 89 e7 b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 4e 5b 5d 41 5c 41 5d 41 5e 41 5f c3 0f 1f 00 RSP: 002b:00007ffd0cc092b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 000000000045987a RDX: 0000000000000003 RSI: 0000000000021000 RDI: 0000000000000000 RBP: ffffffffffffffff R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000020022 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000021000 R14: 0000000000020022 R15: 0000000000000000 INFO: task syz-executor.3:7738 blocked for more than 144 seconds. Not tainted 5.7.0-rc2-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D28584 7738 6856 0x80004004 Call Trace: context_switch kernel/sched/core.c:3372 [inline] __schedule+0x85b/0x1950 kernel/sched/core.c:4088 schedule+0xc3/0x2b0 kernel/sched/core.c:4163 rwsem_down_read_slowpath+0x568/0xfd0 kernel/locking/rwsem.c:1099 __down_read kernel/locking/rwsem.c:1341 [inline] down_read+0x1f5/0x430 kernel/locking/rwsem.c:1494 exit_mm kernel/exit.c:445 [inline] do_exit+0x5e9/0x2bf0 kernel/exit.c:782 do_group_exit+0xf4/0x2e0 kernel/exit.c:893 get_signal+0x36c/0x1d30 kernel/signal.c:2735 do_signal+0x87/0x28d0 arch/x86/kernel/signal.c:784 exit_to_usermode_loop+0x114/0x2e0 arch/x86/entry/common.c:161 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_64+0x531/0x630 arch/x86/entry/common.c:305 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x459829 Code: 24 28 4c 89 6c 24 30 4c 89 64 24 38 4c 89 5c 24 40 4c 89 54 24 48 4c 89 4c 24 50 4c 89 44 24 58 48 89 7c 24 60 48 89 74 24 68 <48> 89 6c 24 70 48 89 5c 24 78 48 89 94 24 80 00 00 00 48 8b 94 24 RSP: 002b:00007f5ca3c7bcf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000075bf28 RCX: 0000000000459829 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000075bf28 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bf2c R13: 00007ffd0cc0935f R14: 00007f5ca3c7c9c0 R15: 000000000075bf2c INFO: task syz-executor.3:7753 blocked for more than 145 seconds. Not tainted 5.7.0-rc2-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D28656 7753 6856 0x80004004 Call Trace: context_switch kernel/sched/core.c:3372 [inline] __schedule+0x85b/0x1950 kernel/sched/core.c:4088 schedule+0xc3/0x2b0 kernel/sched/core.c:4163 rwsem_down_read_slowpath+0x568/0xfd0 kernel/locking/rwsem.c:1099 __down_read kernel/locking/rwsem.c:1341 [inline] down_read+0x1f5/0x430 kernel/locking/rwsem.c:1494 acct_collect+0xd3/0x7b0 kernel/acct.c:544 do_exit+0x507/0x2bf0 kernel/exit.c:774 do_group_exit+0xf4/0x2e0 kernel/exit.c:893 get_signal+0x36c/0x1d30 kernel/signal.c:2735 do_signal+0x87/0x28d0 arch/x86/kernel/signal.c:784 exit_to_usermode_loop+0x114/0x2e0 arch/x86/entry/common.c:161 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_64+0x531/0x630 arch/x86/entry/common.c:305 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x459829 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f5ca3c5acf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000075bfd0 RCX: 0000000000459829 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000075bfd0 RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bfd4 R13: 00007ffd0cc0935f R14: 00007f5ca3c5b9c0 R15: 000000000075bfd4 INFO: task syz-executor.3:7756 blocked for more than 147 seconds. Not tainted 5.7.0-rc2-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D29928 7756 7753 0x80000000 Call Trace: context_switch kernel/sched/core.c:3372 [inline] __schedule+0x85b/0x1950 kernel/sched/core.c:4088 schedule+0xc3/0x2b0 kernel/sched/core.c:4163 rwsem_down_read_slowpath+0x568/0xfd0 kernel/locking/rwsem.c:1099 __down_read kernel/locking/rwsem.c:1341 [inline] down_read+0x1f5/0x430 kernel/locking/rwsem.c:1494 acct_collect+0xd3/0x7b0 kernel/acct.c:544 do_exit+0x507/0x2bf0 kernel/exit.c:774 do_group_exit+0xf4/0x2e0 kernel/exit.c:893 __do_sys_exit_group kernel/exit.c:904 [inline] __se_sys_exit_group kernel/exit.c:902 [inline] __x64_sys_exit_group+0x39/0x40 kernel/exit.c:902 do_syscall_64+0xca/0x630 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x459829 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f5ca3c5a688 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 000000000000000b RCX: 0000000000459829 RDX: 0000000000459829 RSI: 00007f5ca3c5a6c0 RDI: 000000000000000b RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: ffffffffffffffff R11: 0000000000000246 R12: 00007f5ca3c5b6d4 R13: 00000000004bfce6 R14: 00000000004d1a38 R15: 00000000ffffffff INFO: task syz-executor.2:7762 blocked for more than 148 seconds. Not tainted 5.7.0-rc2-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D27320 7762 6851 0x80004004 Call Trace: context_switch kernel/sched/core.c:3372 [inline] __schedule+0x85b/0x1950 kernel/sched/core.c:4088 schedule+0xc3/0x2b0 kernel/sched/core.c:4163 rwsem_down_read_slowpath+0x568/0xfd0 kernel/locking/rwsem.c:1099 __down_read kernel/locking/rwsem.c:1341 [inline] down_read+0x1f5/0x430 kernel/locking/rwsem.c:1494 exit_mm kernel/exit.c:445 [inline] do_exit+0x5e9/0x2bf0 kernel/exit.c:782 do_group_exit+0xf4/0x2e0 kernel/exit.c:893 get_signal+0x36c/0x1d30 kernel/signal.c:2735 do_signal+0x87/0x28d0 arch/x86/kernel/signal.c:784 exit_to_usermode_loop+0x114/0x2e0 arch/x86/entry/common.c:161 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_64+0x531/0x630 arch/x86/entry/common.c:305 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x45987a Code: 89 f5 41 54 49 89 fc 55 53 74 35 49 63 e8 48 63 da 4d 89 f9 49 89 e8 4d 63 d6 48 89 da 4c 89 ee 4c 89 e7 b8 09 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 4e 5b 5d 41 5c 41 5d 41 5e 41 5f c3 0f 1f 00 RSP: 002b:00007ffda31fe6c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 000000000045987a RDX: 0000000000000003 RSI: 0000000000021000 RDI: 0000000000000000 RBP: ffffffffffffffff R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000020022 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000021000 R14: 0000000000020022 R15: 0000000000000000 INFO: task syz-executor.2:7766 blocked for more than 149 seconds. Not tainted 5.7.0-rc2-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D28584 7766 6851 0x80004004 Call Trace: context_switch kernel/sched/core.c:3372 [inline] __schedule+0x85b/0x1950 kernel/sched/core.c:4088 schedule+0xc3/0x2b0 kernel/sched/core.c:4163 rwsem_down_read_slowpath+0x568/0xfd0 kernel/locking/rwsem.c:1099 __down_read kernel/locking/rwsem.c:1341 [inline] down_read+0x1f5/0x430 kernel/locking/rwsem.c:1494 exit_mm kernel/exit.c:445 [inline] do_exit+0x5e9/0x2bf0 kernel/exit.c:782 do_group_exit+0xf4/0x2e0 kernel/exit.c:893 get_signal+0x36c/0x1d30 kernel/signal.c:2735 do_signal+0x87/0x28d0 arch/x86/kernel/signal.c:784 exit_to_usermode_loop+0x114/0x2e0 arch/x86/entry/common.c:161 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_64+0x531/0x630 arch/x86/entry/common.c:305 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x459829 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f6232c0bcf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000075bf28 RCX: 0000000000459829 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000075bf28 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bf2c R13: 00007ffda31fe76f R14: 00007f6232c0c9c0 R15: 000000000075bf2c INFO: task syz-executor.2:7768 blocked for more than 151 seconds. Not tainted 5.7.0-rc2-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D28112 7768 6851 0x80004004 Call Trace: context_switch kernel/sched/core.c:3372 [inline] __schedule+0x85b/0x1950 kernel/sched/core.c:4088 schedule+0xc3/0x2b0 kernel/sched/core.c:4163 rwsem_down_read_slowpath+0x568/0xfd0 kernel/locking/rwsem.c:1099 __down_read kernel/locking/rwsem.c:1341 [inline] down_read+0x1f5/0x430 kernel/locking/rwsem.c:1494 acct_collect+0xd3/0x7b0 kernel/acct.c:544 do_exit+0x507/0x2bf0 kernel/exit.c:774 do_group_exit+0xf4/0x2e0 kernel/exit.c:893 get_signal+0x36c/0x1d30 kernel/signal.c:2735 do_signal+0x87/0x28d0 arch/x86/kernel/signal.c:784 exit_to_usermode_loop+0x114/0x2e0 arch/x86/entry/common.c:161 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_64+0x531/0x630 arch/x86/entry/common.c:305 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x459829 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f6232beacf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000075bfd0 RCX: 0000000000459829 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 000000000075bfd0 RBP: 000000000075bfc8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bfd4 R13: 00007ffda31fe76f R14: 00007f6232beb9c0 R15: 000000000075bfd4 INFO: task syz-executor.2:7769 blocked for more than 152 seconds. Not tainted 5.7.0-rc2-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D29200 7769 7768 0x80000000 Call Trace: context_switch kernel/sched/core.c:3372 [inline] __schedule+0x85b/0x1950 kernel/sched/core.c:4088 schedule+0xc3/0x2b0 kernel/sched/core.c:4163 rwsem_down_read_slowpath+0x568/0xfd0 kernel/locking/rwsem.c:1099 __down_read kernel/locking/rwsem.c:1341 [inline] down_read+0x1f5/0x430 kernel/locking/rwsem.c:1494 acct_collect+0xd3/0x7b0 kernel/acct.c:544 do_exit+0x507/0x2bf0 kernel/exit.c:774 do_group_exit+0xf4/0x2e0 kernel/exit.c:893 __do_sys_exit_group kernel/exit.c:904 [inline] __se_sys_exit_group kernel/exit.c:902 [inline] __x64_sys_exit_group+0x39/0x40 kernel/exit.c:902 do_syscall_64+0xca/0x630 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x459829 Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00